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- An improvement of photocatalytic activity of TiO2 Degussa P25 powderPublication . Bessergenev, V.; Mateus, M. C.; Botelho do Rego, A. M.; Hantusch, M.; Burkel, E.The photocatalytic activities of Degussa P25 powders annealed at various temperatures in vacuum and air were studied together with investigations of their compositions by XPS, of their crystal structures by XRD and of their specific surface areas by BET. It is shown that the photocatalytic activity of P25 powders was remarkably enhanced after vacuum annealing; the kinetic coefficient can be raised by 75% during annealing at 400 degrees C. It is obvious that this enhancement is not related to the adhesion ability of the P25 powders. (C) 2015 Elsevier B.V. All rights reserved.
- TiO2:(Fe, S) Thin Films Prepared from Complex Precursors by CVD, Physical Chemical Properties, and PhotocatalysisPublication . Bessergenev, V.; Mateus, Maria da Conceição; Vasconcelos, D. A.; Mariano, José; do Rego, A. M. Botelho; Lange, R.; Burkel, E.The TiO2 thin films were prepared using Ti(dpm)(2)(OPri)(2) and Ti(OPri)(4) (dpm = 2,2,6,6-tetramethylheptane-3,5-dione, Pr-i = isopropyl) as the precursors. The volatile compounds Fe[(C2H5)(2)NCS2](3) and [(CH3)C](2)S-2 were used to prepare doped TiO2 films. The synthesis was done in vacuum or in the presence of Ar and O-2. The pressure in the CVD chamber was varied between 1.2 x 10(-4) mbar and 0.1 mbar, with the system working either in the molecular beam or gas flow regime. Physical, chemical, and photocatalytic properties of the (Fe, S)-doped TiO2 films were studied. Those TiO2:(Fe, S) films prepared from the Ti(OPri)(4) precursor show increased photocatalytic activities, very close to those of Degussa P25 powder in UV region.
- Structural and magnetic properties of P25 TiO2 nanoparticles doped by CoPublication . Morais Lopes, Fernando; Bessergenev, Valentin; J. Lourenço, João Paulo Lourenço; Hantusch, Martin; Burkel, Eberhard; Botelho do Rego, Ana M.; Rajnak, Michal; Timko, Milan; Kopcansky, PeterThe present work reports on the structural and magnetic properties of TiO2 P25 Degussa powder doped with cobalt. Dissolution of cobalt in TiO2 matrix was achieved by precipitation of tris(diethyldithiocarbamato) cobalt (III) (CoDtc - Co[S2CN(C2H5)(2)](3) in chloroform (CHCl3) and consequent thermal treatment. Five different Co atomic percentage contents were chosen, e.g., 0.5%, 1%, 2%, 5% and 10%. It was shown that cobalt atoms are uniformly distributed across TiO2 matrix and exhibit antiferromagnetic interactions at low temperatures.